Upsilon-type belt



C. W. YELM v-TYPE BELT Sept. l, 1942.

Filed April 4, 1941 FIQZ FMH-

1 UWENTOR.4 ER YE L M @TToK/vev I CHARLESWALT Y Patented Sept. l, 1942v-'rYPE BELT Charles Walter Yelm, Denver, Colo.,

The Gates Rubber Company, corporation of Colorado assgnor to Denver,Colo., a

Application April 4, 1941, Serial No. 386,810 2 claims. v(el. 'f4-234)This invention relates to improvements in flexible belts of the V-typeand more particularly to V-type side driving belts of greater width thanA thickness.

In various types of power transmission it is desirable to employ agrooved pulley in combination with a flat surfaced pulley and for suchtypes of belt drives a belt is required which will function equally wellwith both types of pulleys. Such belts are usually of greater width thanthickness and are preferably outwardly transversely convex so as to moreeffectively resist the action of forces tending to bend the beltinwardly when passing over a grooved pulley and to increase the pressureagainst the driving sides of the grooves in the grooved pulleys.

For convenience in manufacturing'and for the purpose of saving materialsuch belts are provided on their inner surfaces with a longitudinallyextending depression whose surface never contacts the outer surface of aat pulley. Since the flat pulleys do not engage the edges of the belt asa grooved pulley does it does not oppose the tendency of the belt tospread laterally and the tension in thebelt therefore tends to bend thebelt inwardly thereby shifting the forces from the center towards theedges and as a result the strains along the sides or edges of the beltbecome excessive thereby shortening the life of the belt.

It is an object of this invention to produce a belt of the type referredto above which will not materially alter its transverse shape in passingover a fiat surfaced pulley and which will therefore limit the shiftingof the tension strains towards the edges.

Another object is to produce a belt of the above type which maintains aconstant area per unit length in contact with the surface of a fiatpulley regardless of the belt tension.

The above and any other objects that may become apparent asthisdescription proceeds are Figure 4 is a cross section of a beltshowing another slightly modified form of construction.

It has been pointed out above .that V-type side driving belts,especially those that have greater width than thickness, have a tendencyto bend inwardly and decrease the tension of the cordsfrom the edges ofthe belt towards the mid- 'dle when the belt is operating to transmitpower.

Since belts of this type are provided with one or more layers of cordthat extend longitudinally and which constitute a tension resistingcoreit is important that the belt be so constructed that the tensionalstrain isl distributedas equally as possible among the cords of the coreand for this-purpose the belt should be so constructed that the inwardbending is reduced to a minimum during operation.

In the present invention the belt is formed from an inner layer orcushion 5 of comparative soft rubber on which is supported a layer 6 ofcords which occupies a position adjacent the neutral axis of the belt,on the upper or outer surface of the cord layer is another layer pfrubber composition which has been designated by reference numeral l andwhich may be so compounded that it is harder than the inner layer. Ifdesired, the outer layer may be corrugated transversely of the belt assuggested in the prior art. p

Referring now more particularly to Figure 1 where the belt has beenshown as positioned in a grooved pulley 8 and in which the inclinedsides of the groove have been designated by reference numeral 9, it willbe seen that the belt' does not bottom in the groove and that it hasinclined sides l0 which engage the sides 9 of the pulley to provide thenecessary frictional contact.

It will be observed -that the belt is'outwardly v tion being to producean arch that resists forces obtained by means of a construction thatwill now be described in detail and for this purpose reference will behad to the accompanying drawing in which the invention has beenillustrated, and in which:

Figure 1 is a transverse section of a belt embodying the presentinvention showing the same in position in a grooved pulley;

tending to bend the belt inwardly during operation. Due to the resilientand yielding nature of' the material employed, there will always beFigure 2 is a transverse section showing the belt in position on a flatsurfaced pulley;

Figure 3 is a. cross section of a belt showing a slightly modifiedformof construction; and

some inward transverse flexure of such a belt during operation, but due'to the resistance offered by the sides 9, the inward lexure will be lessthan if the belt was transversely straight.

In Figure 2, the belt has been shown in engagement with the outersurface of a ilat surfaced' pulley Il. It is frequentlyy necessary inbelt transmissions to' employ a. grooved pulley in combination with aflat surfaced pulley. Due to the fact that the fiat surfaced pulleyshave no side walls corresponding to the walls'9 of the groove If theinner surface of a belt is made straight,

l it will not ex inwardly when in driving contact with a flat surfacepulley. For reasons which will hereinafter appear, it is necessary todepress the inner surface of the belt leaving two ribs I4 along eachside for engaging the pulley surface. A belt so made will ex inwardlydue to the tension to which it is subjected and this reduces the tensionin the cords near the middle of the belt and subjects the cords near theedges to an excessive tension. To prevent the transfer of tension fromthe center cords to the cords near the edges of the belt, it isnecessary to provide one or more supporting ribs I3 that limit theinward flexing of the belt when passing over a flat surfaced pulley.When the belt is free from tension, the inner surfaces of ribs I3 and I4are in a straight line. The belt may therefofe be defined as having atransversely straight inner driving surface provided with spaced groovesor as having a concave or depressed inner surface provided with spacedparallel ribs.

The presence of the grooves I2 is-due to the fact that when the belt ismanufactured the material is arranged in transversely at layers and isgiven its arched shape during the curing operation ln the mold. Anotherreason for the grooves I2 is that a, considerable amount of material isthus saved over what would be required if such grooves were absent.Since the flat pulleys are nearly always of much larger diameter thanthe grooved pulleys with which they cooperate, the surface area incontact is sufficient for the purpose of transmitting the power evenwith the two grooves I2. In the embodiment shown in Figure 2, the partsof the belt that contact with the pulley have been designated byreference numerals I3 and I4. It is apparent that the rib I3 is veryeffective for re` SiSting inward bending of the belt while passingaround the flat surfaced pulley and therefore the decrease in tension ofthe cords nearer the middle of the belt is greatly limited over what itwould be if the center rib I3 were absent.

Since the surfaces I3 and I`4 act as friction surfaces only while incontact with the large flat surfaced pulley, they may be quite narrowand in the embodiment shown in Figures l, 2 and 4 the combined widths ofgrooves I2 is greater.

than half the width of the belt leaving the combined width of thefriction surfaces I3 and I4 less than half the width of the belt. Thisrelationship may prevail regardless of the number of grooves. Thegreater the total widths of groove I2 are, the more effectively thetransverse arching of the cord layer can be effected.

Attention is called at this point to the fact that the belt may beprovided with the usual covering of bias cut rubberized fabric which hasbeen indicated at I5 in Figure 2.

In Figure 4, a belt has been shown whose cross section differs from thatshown in Figures 1 and 2, in this. that the outer surface istransversely straight instead of convex. The reason for the crosssectional shape shown in Figure 4 is to produce a belt that can transmitpower from both its inner and outer surface and also along its inclinededges I0. It sometimes happens that a belt power transmission requirestwo flat pulleys in combination with one grooved pulley and in suchcases one of the flat pulleys contact the outer surface of the beltwhile the other flat pulley is in contact with the inner surface.

Particular attention is called to the fact that in its normal shape theinner surface of the belt is transversely straight, regardless ofwhether the outer surface is convex as shown invFlgures l, 2 and 3 orstraight as shown in Figure 4. It is apparent that a belt of theconstruction here shown and described has a constant area of contact perunit length with the outer surface of a flat pulley and that this doesnot change due to changes in belt tension.

From the above description when taken in connection with the drawing, itwill be seen that the belt that forms the subject of this invention isso constructed that the changes in the tension of the cords will berestricted to a minimum during operation due to the fact that there canbe no inward transverse iiexure of the belt while passing over the iiatsurfaced pulley and any flexure that takes place will therefore belimited to the comparatively small flexing whi passing over the groovedpulley.

Although this invention has been shown and described in connection withbelts of greater width than thickness, it is to be understood that thisis not an essential limitation for the reason that V-type sidedrivingbelts are frequently quite thick and may therefore have suillcient widthto flex to an objectionable extent even if they have less width thanthickness.

Having described the invention what is claimed as new is:

l. A combined edge and inside driving belt -for use with V-grooved andnat surfaced pulleys,

said belt having at least one transversely extending outwardly convexlayer of tension resisting cords 'embedded therein and extendinglengthwise thereof, the inner surface of the belt having a frictionsurface along each edge, the surface between the two friction surfacesbeing depressed, the depressed surface having at least one inwardlyextending rib adapted to engage the outside of a fiat surfaced pulley toresist forces tending to flex the belt inwardly toward the surface ofthe pulley and thereby limit the decrease in tension of the cordsnearest the middle of the layer, the friction surfaces and thecorresponding surface of the rib being normally in a straight linetransverse of the belt.

2. An endless belt of the side driving'V-type y

